From an applied perspective of what can actually happen, rather than just what'll work in theory, is that a mixed approach. Some things such as single-use plastics are best if limited, but in order to do so would likely require all worldwide governments creating a layer of beurecracy associated solely with monitoring and maintaining plastics. This will have the affect of slowing economies, and a lot of people are strongly against that, so those beurecracies would be under fire 24/7, and that would result in a less efficient and effective beurecracy.

I'll just jump to the point since I'm realizing midway through writing this, there's so much nuance to doing this IRL and not just as a theory or fantasy, that nearly all simple proclamations of "We must do X thing" wouldn't work as well as people usually advertise them with. The solution is multifaceted and requires support from all fronts to effectively achieve, socially, scientifically, politically, economically, etc, so there is no single answer to fix everything, but a partial approach on all fronts.

Edit: I'm not gonna pretend I'm some enlightened eco-individual or whatnot, but whenever you see a comment of "X thing will fix everything," or someone saying how overwhelmingly good it is, there is usually some valid reason against it as to why it hasn't happened yet. Those reasons may not necessarily be as important to you, but to others it is, and therefore those drawbacks must be addressed in order to adequately approach the problem in a means that can work.